1. Field of the Invention
In general, this invention relates to blood glucose measuring devices and techniques. More particularly, this invention relates to systems and methods that can measure blood glucose in the body without the need to draw a blood sample.
2. Prior Art Description
Diabetes is a chronic disease without a cure. Over twenty five million people in the United States of America have diabetes. Diabetes is the seventh leading cause of death in the United States. Currently, diabetes is estimated to cost the United States health care system over one-hundred billion dollars annually.
Diabetes creates high blood glucose levels due to a deficiency of insulin production and action. This failure leads to hyperglycemia. Persistent hyperglycemia causes a variety of serious symptoms and life threatening long term complications such as dehydration, diabetic coma, cardiovascular disease, and poor blood circulation.
Many diabetics are required to take insulin in order to control the glucose levels in their blood. However, having insulin levels in the blood that are too high are just as dangerous as having insulin levels in the blood that are too low. Consequently, it is critical that diabetics who use insulin precisely monitor the level of glucose in their bodies.
The most common and accurate glucose monitoring techniques require that a blood sample be drawn from the body. This is typically done by pricking the skin with a needle or lancet to obtain a small droplet of blood. The blood is placed upon a chemically treated strip of paper. The strip of paper is then placed in a glucometer, which tests the blood and provides a glucose level reading.
Pricking the skin can be painful. Areas of the skin can also experience increased sensitivity to pain if those areas are repeatedly pricked over long periods of time. Furthermore, many diabetics have blood circulation problems. As a result, these diabetics can only draw blood from certain parts of the body, such as the fingertips, where good blood flow remains. Unfortunately, the areas of the body that have good blood flow often correspond to the areas of the body that have a high concentration of nerve endings, thus increasing the pain associated with obtaining such a blood sample. The result often is that diabetics are deterred from testing and consequently test their blood glucose levels far less often than they should.
For the reasons stated above, there has been a long standing need for a glucose monitoring device that can detect the level of glucose in a diabetic without the need for a drawn blood sample. In the prior art, certain devices have been produced that claim that they can meet this need. For instance, in U.S. Patent App. Pub. No. 2010/0112614 to Axelrod, entitled Coupled Antenna Impedance Spectroscopy, a methodology is presented for measuring blood glucose levels. However, the technique does not produce accurate results in comparison to common blood drawn testing techniques. More importantly, such methodologies require the use of a spectroscope. Consequently, such testing systems are limited to use in hospitals and labs that have spectroscopes. Such testing systems cannot be made into low-cost portable devices using known technologies.
In U.S. Pat. No. 9,078,606, to Bharj, the Applicant presented an earlier design for a passive glucose monitoring system that measures blood glucose levels using a microwave resonance chamber. However, in order for the system to function properly, a mass of skin has to be pressed against a hole in the microwave resonance chamber so that some of the skin and body tissue bulges through the hole and into the microwave resonance chamber. This requirement mandates that the resonance chamber be relatively large in order to receive the tissue needed for an accurate test. As such, the system cannot be miniaturized to any significant degree without causing adverse affects to the monitoring accuracy.
Many diabetics carry insulin pumps that automatically pump insulin into the bloodstream at a selected rate. Insulin pump systems are designed to be as small and discrete as possible so that the systems can be comfortably worn without being seen. Insulin pump systems typically rely upon a person's average blood sugar levels, as monitored over time. The problem is that many diabetics fluctuate from their averages as they rest, exercise, eat, and drink. Insulin pumps can be made much more effective if the system were capable of constantly monitoring blood sugar levels in real time. In this manner, the system could inject insulin only when insulin was needed. To monitor blood levels in this manner, a passive blood monitoring system is required that does not require blood contact and can be made small enough so as to not to increase the size of insulin pumps to any significant degree.
This need is met by the present invention as described and claimed below.